Biological Dosimeter Research Articles

Determination of dose-response calibration curves for gamma radiation using gamma-H2AX immunofluorescence based biodosimetry.

Gamma-H2AX immunofluorescence assay has gained popularity as a DNA double strand break marker. In this work, we have investigated the potential use of gamma H2AX immunofluorescence assay as a biological dosimeter for estimation of dose in our institution. Seven healthy individuals were selected for the study and the blood samples collected from the first five individuals were irradiated to low doses (0-10 cGy) and high doses (50-500 cGy) in a telecobalt unit. All the samples were processed for gamma-H2AX immunofluorescence assay and the dose-response calibration curves for low and high doses were determined. In order to validate the determined dose-response calibration curves, the blood samples obtained from the sixth and seventh subjects were delivered a test dose of 7.5 cGy and 250 cGy. In addition, time and cost required to complete the assay were also reported. The goodness of fit (R2) values was found to be 0.9829 and 0.9766 for low and high dose-response calibration curves. The time required to perform the gamma-H2AX immunofluorescence assay was found to be 7 hours and 30 minutes and the estimated cost per sample was 5000 rupees (~ 60 USD). Based on this study we conclude that the individual dose-response calibration curves determined with gamma-H2AX immunofluorescence assay for both low and high dose ranges of gamma radiation can be used for biological dosimetry. Further, the gamma-H2AX immunofluorescence assay can be used as a rapid cost-effective biodosimetric tool for institutions with an existing confocal microscope facility.

Candidate biomarkers and persistent transcriptional responses after low and high dose ionizing radiation at high dose rate

Purpose Development of an integrated time and dose model to explore the dynamics of gene expression alterations and identify biomarkers for biodosimetry following low- and high-dose irradiations at high dose rate. Material and methods We utilized multiple transcriptome datasets (GSE8917, GSE43151, and GSE23515) from Gene Expression Omnibus (GEO) for identifying candidate biological dosimeters. A linear mixed-effects model with random intercept was used to explore the dose-time dynamics of transcriptional responses and to functionally characterize the time- and dose-dependent changes in gene expression. Results We identified genes that are correlated with dose and time and discovered two clusters of genes that are either positively or negatively correlated with both dose and time based on the parameters of the model. Genes in these two clusters may have persistent transcriptional alterations. Twelve potential transcriptional markers for dosimetry—ARHGEF3, BAX, BBC3, CCDC109B, DCP1B, DDB2, F11R, GADD45A, GSS, PLK3, TNFRSF10B, and XPC were identified. Of these genes, BAX, GSS, and TNFRSF10B are positively associated with both dose and time course, have a persistent transcriptional response, and might be better biological dosimeters. Conclusions With the proposed approach, we may identify candidate biomarkers that change monotonically in relation to dose, have a persistent transcriptional response, and are reliable over a wide dose range.

Optical Fibers as Dosimeter Detectors for Mixed Proton/Neutron Fields—A Biological Dosimeter

In recent years, proton therapy has gained importance as a cancer treatment modality due to its conformality with the tumor and the sparing of healthy tissue. However, in the interaction of the protons with the beam line elements and patient tissues, potentially harmful secondary neutrons are always generated. To ensure that this neutron dose is as low as possible, treatment plans could be created to also account for and minimize the neutron dose. To monitor such a treatment plan, a compact, easy to use, and inexpensive dosimeter must be developed that not only measures the physical dose, but which can also distinguish between proton and neutron contributions. To that end, plastic optical fibers with scintillation materials (Gd2O2S:Tb, Gd2O2S:Eu, and YVO4:Eu) were irradiated with protons and neutrons. It was confirmed that sensors with different scintillation materials have different sensitivities to protons and neutrons. A combination of these three scintillators can be used to build a detector array to create a biological dosimeter.

The Association of Radiation Exposure with Stable Chromosome Aberrations in Atomic Bomb Survivors Based on DS02R1 Dosimetry and FISH Methods.

The frequency of stable chromosome aberrations (sCA) in lymphocytes is a recognized radiation biological dosimeter. Its analysis can provide insights into factors that affect individual susceptibility as well as into the adequacy of radiation dose estimates used in studies of atomic bomb survivors. We analyzed the relationship between atomic bomb radiation exposure using the most recent DS02R1 dose estimates and the frequency of sCA as determined by FISH in 1,868 atomic bomb survivors. We investigated factors that may affect the background sCA rate and the shape and magnitude of the dose response. As in previous analyses of sCA in atomic bomb survivors that were based on Giemsa staining methods and used older DS86 dose estimates, the relationship between radiation dose and sCA rate was significant (P < 0.0001) with a linear-quadratic relationship at lower doses that did not persist at higher doses. As before, age at the time of the bombing and type of radiation shielding were significant dose-effect modifiers (P < 0.0001), but in contrast the difference in dose response by city was not so pronounced (P = 0.026) with a city effect not evident at doses below 1.25Gy. Background sCA rate increased with age at the time of examination (P < 0.0001), but neither sex, city, nor smoking was significantly associated with background rate. Based on FISH methods and recent dosimetry, the relationship between radiation dose and sCA frequency is largely consistent with previous findings, although the lesser importance of city as an effect modifier may reflect better dosimetry as well as more reproducible scoring of sCA. The persisting difference in sCA dose response by shielding category points to remaining problems with the accuracy or precision of radiation dose estimates in some A-bomb survivors.

Fish otoliths as biological dosimeter: internal dose calculation.

Otoliths are organs used by fish for hearing and keeping balance. They consist of biogenic crystals of hydroxyapatite and do not contain any living cells. Upon exposure to ionizing radiation, otolith hydroxyapatite accumulates radiation-induced stable CO2- radicals whose amount is proportional to absorbed dose. In electron paramagnetic resonance (EPR) dosimetry, carbonate ions are registered and, hence, the total accumulated dose in the fish otolith can be quantified. Therefore, otoliths can be used as individual fish dosimeters to support radiobiological and radioecological studies. An important aspect of otolith-based EPR dosimetry on fish from contaminated water bodies is the potential presence of bone-seeking 90Sr. Consequently, cumulative absorbed doses measured with EPR in otoliths may reflect the superposition of internal exposure to 90Sr/90Y and external exposure due to radionuclides circulating in soft tissue of the fish as well as due to environmental contamination. The objective of the present study was to develop a method that allows for an assessment of the contribution of 90Sr to the total dose in otolith. The method has been tested using otoliths from seven fish taken from reservoirs located in the Southern Urals contaminated with radionuclides including 90Sr. It has been shown that dose to otoliths is largely determined by 90Sr in the hydroxyapatite. The internal dose component can be calculated using activity concentration-to-dose conversion factors, which vary slightly in the range of 2.0-2.8 × 10-3Gyyear-1 perBqg-1 depending on fish species and age. Internal doses to fish from water bodies with different levels of 90Sr contamination were calculated in the range from 2mGy to ~ 200Gy. External dose contribution was derived for two fish only to be about 100 and 40Gy. It is concluded that EPR dosimetry on fish otoliths is a promising tool when external exposure prevails or is comparable to internal exposure due to 90Sr.

An estimate assay for low-level exposure to ionizing radiation based on mass spectrometry quantification of γ-H2AX in human peripheral blood lymphocytes.

Exposure to environmental ionizing radiation (IR) is ubiquitous, and large-dose exposure to IR is known to cause DNA damage and genotoxicity which is associated with an increased risk of cancer. Whether such detrimental effects are caused by exposure to low-dose IR is still debated. Therefore, rapid and early estimation of absorbed doses of IR in individuals, especially at low levels, using radiation response markers is a pivotal step for early triage during radiological incidents to provide adequate and timely clinical interventions. However, there is currently a crucial shortage of methods capable of determining the extent of low-dose IR exposure to human beings. The phosphorylation of histone H2AX on serine 139 (designated γ-H2AX), a classic biological dosimeter, can be used to evaluate the DNA damage response. We have developed an estimation assay for low-level exposure to IR based on the mass spectrometry quantification of γ-H2AX in blood. Human peripheral blood lymphocytes sensitive to low-dose IR, maintaining low temperature (4°C) and adding enzyme inhibitor are proven to be key steps, possibly insuring that a stable and marked γ-H2AX signal in blood cells exposed to low-dose IR could be detected. For the first time, DNA damage at low dose exposures to IR as low as 0.01 Gy were observed using the sensitive variation of γ-H2AX with high throughput mass spectrometry quantification in human peripheral blood, which is more accurate than the previously reported methods by virtue of isotope-dilution mass spectrometry, and can observe the time effect of DNA damage. These in vitro cellular dynamic monitoring experiments show that DNA damage occurred rapidly and then was repaired slowly over the passage of post-irradiation time even after exposure to very low IR doses. This assay was also used to assess different radiation exposures at the in vitro cellular level. These results demonstrate the potential utility of this assay in radiation biodosimetry and environmental risk assessment.

Transformed Cell Ratio (TCR): A Novel Parameter for Radiation Dose Estimation in Rapid Premature Chromosome Condensation (PCC) Assay Induced by 0–40 Gy Co-60 Gamma Rays

Abstract Calyculin A-induced premature chromosome condensation (PCC) assay is considered a method for estimating radiation dose. In this study, a novel parameter, the transformed cell ratio (TCR), which is the ratio of irradiated and unirradiated lymphocyte transformation rates in the PCC assay, was suggested for dose estimation since it may be correlated with ionizing radiation dose. Human peripheral lymphocytes were irradiated in vitro with 60Co gamma ray doses of 0, 10, 20, 30, and 40 Gy, stimulated with phytohemagglutinin, and incubated for 3, 6, 12, or 48 h, division-blocked with colcemid, and PCC-induced by calyculin A or addition of extra cyclin-dependent kinase 1/cyclin B (CDK1/cyclinB). Results showed that G1-, S-, G2-, and M-PCC cells appeared in human lymphocyte culture, dose-response curves between the absorbed dose and lymphocyte transformation rate or TCR was fitted. TCR presented the best goodness-of-fit to a linear model (y = 0.0097 X +0.9952, R2 = 0.971, P &lt; 0.05) within 0 to 40 Gy. Observations also suggested that TCR is a potential biological dosimeter for assessing received radiation doses ranging from 0 to 40 Gy during radiation exposure.

In Vivo Quantitative Assessment of a Radiation Dose Based on Ratiometric Photoacoustic Imaging of Tumor Apoptosis.

Accurately assessing the radiation level of tumors and surrounding tissues is of great significance for the optimization of clinical therapeutic interventions as well as minimizing the radiation-induced side effects. Therefore, the development of noninvasive and sensitive biological dosimeters is vital to achieve quantitative detection of a radiation dose in a living system. Herein, as a proof of concept, we report a tumor-targeted and caspase-3-activatable NIR fluorogenic probe AcDEVD-Cy-RGD consisting of a hemicyanine fluorophore as a signal reporter, a caspase-3 specific Asp-Glu-Val-Asp (DEVD) peptide, and a cyclic Arg-Gly-Asp peptide (cRGD) for tumor targeting. Upon cleavage with activated caspase-3, this probe not only displays the lighted-up NIR fluorescence, but also ratiometric photoacoustic (PA710/PA680) signals concurrently in a caspase-3 concentration-dependent manner, allowing for sensitive and quantitative detection of caspase-3 activity through both fluorescence and PA imaging, which provides the possibility for real-time monitoring of tumor cell apoptosis in a living system. More notably, we utilized this probe to successfully realize the direct visualization of tumor response to chemo- or radiotherapy and, for the first time, achieve the accurate estimation of radiation doses imparted to the tumors. We thus believe that our current strategy would offer an attractive and valuable means for the precise assessment of locally delivered radiation doses in various clinical settings.

Positive Cofactor 4 as a Potential Radiation Biodosimeter for Early Assessment.

During a major radiation event, a large number of people need to be rapidly assessed for radiation damage to ensure effective medical treatment and efficient use of medical resources. However, current techniques cannot meet the requirement of rapid detection of large quantities of samples in an emergency. It is essential to develop rapid and accurate radiation biodosimeters in peripheral blood. Here, we identified radiation sensitive genes in mice by RNA sequencing and evaluated their utility as radiation biodosimeters in human cell lines. Mice were subjected to gamma-irradiation with different doses (0–8 Gy, .85 Gy/min), and the tail venous blood was analyzed by RNA sequencing. We have identified 5 genes with significantly differential expression after radiation exposure. We found that positive cofactor 4(PC4) had well correlation with radiation dose in human lymphoblastoid cell line after irradiation. The relative expression of PC4 gene showed a good linear correlation with the radiation dose after 1–5 Gy irradiation (.85 Gy/min). PC4 gene can be rapidly recruited to the DNA damage sites faster than γ-H2AX after radiation in immunofluorescence detection. In conclusion, PC4 may be represented as new radiation biological dosimeter for early assessment.

Bringing Light into Darkness-Comparison of Different Personal Dosimeters for Assessment of Solar Ultraviolet Exposure.

(1) Measuring personal exposure to solar ultraviolet radiation (UVR) poses a major challenges for researchers. Often, the study design determines the measuring devices that can be used, be it the duration of measurements or size restrictions on different body parts. It is therefore of great importance that measuring devices produce comparable results despite technical differences and modes of operation. Particularly when measurement results from different studies dealing with personal UV exposure are to be compared with each other, the need for intercomparability and intercalibration factors between different measurement systems becomes significant. (2) Three commonly used dosimeter types—(polysulphone film (PSF), biological, and electronic dosimeters)—were selected to perform intercalibration measurements. They differ in measurement principle and sensitivity, measurement accuracy, and susceptibility to inaccuracies. The aim was to derive intercalibration factors for these dosimeter types. (3) While a calibration factor between PSF and electronic dosimeters of about 1.3 could be derived for direct irradiation of the dosimeters, this was not the case for larger angles of incidence of solar radiation with increasing fractions of diffuse irradiation. Electronic dosimeters show small standard deviation across all measurements. For biological dosimeters, no intercalibration factor could be found with respect to PSF and electronic dosimeters. In a use case, the relation between steady-state measurements and personal measurements was studied. On average, persons acquired only a small fraction of the ambient radiation.

Study on urine biomarkers of radiation-induced injury guided by Caenorhabditis elegans as a model organism

ObjectiveUnder the guidance of model organism Caenorhabditis elegans with fine olfactory system, small molecular metabolites sensitive to high dose radiation were screened as biomarkers of acute radiation-induced injury, and their metabolic pathways were elucidated by enrichment. MethodsRats were irradiated with 12 ​Gy γ-rays to establish an acute radiation injury model, and their urine was fingerprinted using UPLC-Q/TOF-MS. Further, under the guidance of Caenorhabditis elegans as olfactory-sensitive model organism, the key differential metabolites in urine were found as biomarkers of radiation-induced injury. ResultsAfter rats were irradiated, the radiation injury urine showed a difference from control (sham-irradiated) urine, which could be distinguished by Caenorhabditis elegans. Based on metabolomics analysis, a total of 21 key differential metabolites with P value ​< ​0.05 and fold change either >2 or <0.5 were identified, which can be used as sensitive and reliable biomarkers of radiation-induced injury. The pathways were further enriched, and it was found that disorders of five metabolic pathways, including citric acid cycle and amino acid metabolism, play an important role in radiation-induced injury. ConclusionsDue to radiation injury, the metabolites in urine will change significantly. The study on biomarkers guided by model organism Caenorhabditis elegans provides a new perspective to explain the details of metabolic disorders, and also provides experimental basis for the development of new biological dosimeters.

Establishment of Microbeam Radiation Therapy at a Small-Animal Irradiator

Microbeam radiation therapy is a preclinical concept in radiation oncology. It spares normal tissue more effectively than conventional radiation therapy at equal tumor control. The radiation field consists of peak regions with doses of several hundred gray, whereas doses between the peaks (valleys) are below the tissue tolerance level. Widths and distances of the beams are in the submillimeter range for microbeam radiation therapy. A similar alternative concept with beam widths and distances in the millimeter range is presented by minibeam radiation therapy. Although both methods were developed at large synchrotron facilities, compact alternative sources have been proposed recently. A small-animal irradiator was fitted with a special 3-layered collimator that is used for preclinical research and produces microbeams of flexible width of up to 100 μm. Film dosimetry provided measurements of the dose distributions and was compared with Monte Carlo dose predictions. Moreover, the micronucleus assay in Chinese hamster CHO-K1 cells was used as a biological dosimeter. The focal spot size and beam emission angle of the x-ray tube were modified to optimize peak dose rate, peak-to-valley dose ratio (PVDR), beam shape, and field homogeneity. An equivalent collimator with slit widths of up to 500 μm produced minibeams and allowed for comparison of microbeam and minibeam field characteristics. The setup achieved peak entrance dose rates of 8 Gy/min and PVDRs >30 for microbeams. Agreement between Monte Carlo simulations and film dosimetry is generally better for larger beam widths; qualitative measurements validated Monte Carlo predicted results. A smaller focal spot enhances PVDRs and reduces beam penumbras but substantially reduces the dose rate. A reduction of the beam emission angle improves the PVDR, beam penumbras, and dose rate without impairing field homogeneity. Minibeams showed similar field characteristics compared with microbeams at the same ratio of beam width and distance but had better agreement with simulations. The developed setup is already in use for invitro experiments and soon for invivo irradiations. Deviations between Monte Carlo simulations and film dosimetry are attributed to scattering at the collimator surface and manufacturing inaccuracies and are a matter of ongoing research.

Assessment of absorbed dose of gamma rays using the simultaneous determination of inactive hemoglobin derivatives as a biological dosimeter.

Biological dosimetry based on sulfhemoglobin (SHb), methemoglobin (MetHb), and carboxyhemoglobin (HbCO) levels was evaluated. SHb, MetHb and HbCO levels were estimated in erythrocytes of mice irradiated by γ rays from a 60Co source using the method of multi-component spectrophotometric analysis developed recently. In this method, absorption measurements of diluted aqueous Hb-solution were made at λ = 500, 569, 577 and 620nm, and using the mathematical formulas based on multi-component spectrophotometric analysis and the mathematical Gaussian elimination method for matrix calculation, the concentrations of various Hb-derivatives and total Hb in mice blood were estimated. The dose range of γ rays was from 0.5 to 8Gy and the dose rate was 0.5Gymin-1. Among all Hb-derivatives, MetHb, SHb and HbCO demonstrated an unambiguous dose-dependent response. For SHb and MetHb, the detection limits were about 0.5Gy and 1Gy, respectively. After irradiation, high levels of MetHb, SHb and HbCO persisted for at least 10days, and the maximal increase of MetHb, SHb and HbCO occurred up to 24h following γ irradiation. The use of this "MetHb + SHb + HbCO"-derivatives-based absorbed dose relationship showed a high accuracy. It is concluded that simultaneous determination of MetHb, SHb and HbCO, by multi-component spectrophotometry provides a quick, simple, sensitive, accurate, stable and inexpensive biological indicator for the early assessment of the absorbed dose in mice.

Radiation-Induced Chromosomal Aberrations As Biological Dosimeter to Assess Dose after in-Vivo Radiation Exposure of Head and Neck Cancer Patients Undergoing Radiation Therapy: A Quantitative Analysis

Radiation-Induced Chromosomal Aberrations As Biological Dosimeter to Assess Dose after in-Vivo Radiation Exposure of Head and Neck Cancer Patients Undergoing Radiation Therapy: A Quantitative Analysis

The Quantity and Leukocytes Components as Biological Dosimeters on the Radiation Workers at Radiology Installation RSUP Sanglah Hospital Denpasar

Regularly, the radiation monitoring program is applied to all the radiation workers using physical dosimeter, in the TLD form, badge films and others. The monitoring from the biological aspect is called biological dosimeter as an indicator of the organ damages that caused radiation exposure, especially on the radiation workers in the radiology installation RSUP Sanglah Hospital are not much studied. Objective: This study aims are determining of the quantity and leukocytes components differences that caused environmental radiation exposure in direct contact radiation and direct non-contact radiation workers. Data and method: The research data was obtained through the blood test at RSUP Sanglah Hospital Denpasar with diffraction count method. The extent of the leukocyte component is determined by the absolute count method. The population in this study were 70 people with the total sample were 35 direct radiation radiation workers (30 radiograper people, 5 medical physicists) and 35 direct non-contact radiation workers (12 nurses, 18 administrative personnel, 5 medical records) . Results: Generally, the blood cell quantity values (hemoglobin-HGB, RBC-erythrocyte, leukocyte-WBC), as well as the percentage of WBC components (basifil-Baso, eosinophil-Eos, neotrifil-Neo, lymphocytes -Limfo and Monocyte-Mono) for radiation workers and non-radiation workers are in the normal range. However, in the normal range, radiation workers have a wider range than non-radiation workers, indicating that radiation workers have undergone a stochastic radiation effect. While the quantity of blood cells over the age range of radiation workers and non-radiation workers alike shows the stochastic effect tends to appear in the productive age of 31-40 years old. For the age of 21-30 years is still normal caused by a relatively new work mass. But at the age of 41-50 tends to approximate the deterministic effect, this can be understood because the mass of work that has been long enough. Conclusions: For long time in the  radiation field area which increase the deterministic effect the cells of the human body response. Primarily, biological indicators of radiation as a dosimeter are used.  Â

Methemoglobin-Based Biological Dose Assessment for Human Blood

Methemoglobin is an oxidative form of hemoglobin in erythrocytes. The authors' aim was to develop a new biological dosimeter based on a methemoglobin assay. Methemoglobin in peripheral blood (of females or males) that was exposed to a Co source (0.20 Gy min) was quantified using an enzyme-linked immunosorbent assay. The dose range was 0.5-8.0 Gy. In a time-course experiment, the time points 0, 0.02, 1, 2, 3, 7, 15, 21, and 30 d after 4-Gy irradiation of heparinized peripheral blood were used. Methemoglobin levels in a lysed erythrocyte pellet from the irradiated blood of females and males increased with the increasing dose. Methemoglobin levels in female blood irradiated with γ-doses more than 4 Gy were significantly higher than those in male samples at the same doses. Two dose-response relations were fitted to the straight line: one is with the correlation coefficient of 0.98 for females, and the other is with the correlation coefficient of 0.99 for males. The lower limit of dose assessment based on methemoglobin is about 1 Gy. Methemoglobin levels in blood as a result of auto-oxidation increase after 7-d storage at -20 °C. The upregulation of methemoglobin induced by γ-radiation persists for ∼3 d. The absorbed doses that were estimated using the two dose-response relations were close to the actual doses. The results suggest that methemoglobin can be used as a rapid and accurate biological dosimeter for early assessment of absorbed γ-dose in human blood.

Enhancing Cytogenetic Biological Dosimetry Capabilities of the Philippines for Nuclear Incident Preparedness.

The utility of a biological dosimeter based on the analysis of dicentrics is invaluable in the event of a radiological emergency wherein the estimated absorbed dose of an exposed individual is crucial in the proper medical management of patients. The technique is also used for routine monitoring of occupationally exposed workers to determine radiation exposure. An in vitro irradiation study of human peripheral blood lymphocytes was conducted to establish a dose-response curve for radiation-induced dicentric aberrations. Blood samples were collected from volunteer donors and together with optically stimulated luminescence (OSL) dosimeters and were irradiated at 0, 0.1, 0.25, 0.5, 0.75, 1, 2, 4, and 6 Gy using a cobalt-60 radiotherapy unit. Blood samples were cultured for 48 h, and the metaphase chromosomes were prepared following the procedure of the International Atomic Energy Agency's Emergency Preparedness and Response – Biodosimetry 2011 manual. At least 100 metaphases were scored for dicentric aberrations at each dose point. The data were analyzed using R language program. The results indicated that the distribution of dicentric cells followed a Poisson distribution and the dose-response curve was established using the estimated model, Ydic = 0.0003 (±0.0003) +0.0336 (±0.0115) × D + 0.0236 (±0.0054) × D2. In this study, the reliability of the dose-response curve in estimating the absorbed dose was also validated for 2 and 4 Gy using OSL dosimeters. The data were fitted into the constructed curve. The result of the validation study showed that the obtained estimate for the absorbed exposure doses was close to the true exposure doses.

Chromosomal aberrations and oxidative DNA adduct 8-hydroxy-2-deoxyguanosine as biomarkers of radiotoxicity in radiation workers

BackgroundThere are evidences of association between occupational radiation exposure, cytogenetic alterations and the increase in cancer rates. It is known that the probability of carcinogenesis is greater in populations exposed to radiation, since ionizing radiation can raise the frequency of chromosomal aberration and spontaneous mutations. ObjectiveOur purpose was to assess the role of chromosomal aberrations and oxidative DNA adduct 8-hydroxy-2-deoxyguanosine (8-OHdG) as biomarkers of radiation injury in individuals occupationally exposed to ionizing radiation. Subjectsand Methods: Blood samples were collected from 60 radiation workers and 30 healthy volunteers age and sex matched as control group who had never worked in radiation-related jobs. Chromosomal aberrations in peripheral blood lymphocytes were assayed by conventional cytogenetic technique and serum levels of 8-OHdG was measured by enzyme linked immunossorbent assay (ELISA). ResultsThe incidence of all types of chromosomal aberrations was significantly higher in all exposed groups than in controls with the highest rate of chromosomal aberrations in the industrial radiographers. Serum 8-OHdG in all radiation workers was significantly higher than in control group. There was a significant higher values among industrial radiographers compared to diagnostic radiologists or radiotherapists. Significantly lower mean corpuscular volume (M.C.V) was found among radiation workers versus the controls reflecting erythrocyte microcytosis. ConclusionsScoring of chromosome aberrations such as breaks, fragments and dicentrics is a reliable method to detect previous exposure to ionizing radiation. This type of monitoring may be used as a biological dosimeter instead of physical dosimetry.8-OHdG is a useful oxidative DNA marker among radiation workers and those exposed to environmental carcinogens.

Verification by the FISH translocation assay of historic doses to Mayak workers from external gamma radiation.

The aim of this study was to apply the fluorescence in situ hybridization (FISH) translocation assay in combination with chromosome painting of peripheral blood lymphocytes for retrospective biological dosimetry of Mayak nuclear power plant workers exposed chronically to external gamma radiation. These data were compared with physical dose estimates based on monitoring with badge dosimeters throughout each person's working life. Chromosome translocation yields for 94 workers of the Mayak production association were measured in three laboratories: Southern Urals Biophysics Institute, Leiden University Medical Center and the former Health Protection Agency of the UK (hereinafter Public Health England). The results of the study demonstrated that the FISH-based translocation assay in workers with prolonged (chronic) occupational gamma-ray exposure was a reliable biological dosimeter even many years after radiation exposure. Cytogenetic estimates of red bone marrow doses from external gamma rays were reasonably consistent with dose measurements based on film badge readings successfully validated in dosimetry system "Doses-2005" by FISH, within the bounds of the associated uncertainties.

Assessing patient characteristics and radiation-induced non-targeted effects in vivo for high dose-rate (HDR) brachytherapy

Purpose: To test whether blood, urine, and tissue based colony-forming assays are a useful clinical detection tool for assessing fractionated treatment responses and non-targeted radiation effects in bystander cells.Materials and methods: To assess patients’ responses to radiation treatments, blood serum, urine, and an esophagus explant-based in vivo colony-forming assay were used from oesophageal carcinoma patients. These patients underwent three fractions of high dose rate (HDR) intraluminal brachytherapy (ILBT).Results: Human keratinocyte reporters exposed to blood sera taken after the third fraction of brachytherapy had a significant increase in cloning efficiency compared to baseline samples (p < 0.001). Such results may suggest an induced radioresistance response in bystander cells. The data also revealed a clear inverse dose-rate effect during late treatment fractions for the blood sera data only. Patient characteristics such as gender had no statistically significant effect (p > 0.05). Large variability was observed among the patients’ tissue samples, these colony-forming assays showed no significant changes throughout fractionated brachytherapy (p > 0.05).Conclusion: Large inter-patient variability was found in the urine and tissue based assays, so these techniques were discontinued. However, the simple blood-based assay had much less variability. This technique may have future applications as a biological dosimeter to predict treatment outcome and assess non-targeted radiation effects.